Gm oil visc recommended for the southern states

[Homer1959]

Here in canada they recommend 5w30 with no other choice, what about you guys in the usa living in arizona or texas. No opinion needed, i just need to know what is in you owner manual thanks

[davester]

go to gm's us website and download the us manual.  they don't make state-specific ones, from what I can tell.

[Homer1959]

2 minutes ago, davester said:

go to gm's us website and download the us manual.  they don't make state-specific ones, from what I can tell.

Well, thanks, Davester! I thought about it, and I checked earlier tonight—there's no difference between the U.S. and Canadian owner manuals. The only recommendation is 5W-30 Dexos 1 Gen 3. That feels pretty thin for a working truck hauling in 100°F, but I guess it is what it is. In the past, we always had a chart in the manual that provided some flexibility, but I guess that's no longer the case. 

[Grumpy Bear]

9 hours ago, Homer1959 said:

Well, thanks, Davester! I thought about it, and I checked earlier tonight—there's no difference between the U.S. and Canadian owner manuals. The only recommendation is 5W-30 Dexos 1 Gen 3. That feels pretty thin for a working truck hauling in 100°F, but I guess it is what it is. In the past, we always had a chart in the manual that provided some flexibility, but I guess that's no longer the case. 

 

My first vehicles had owners manuals that told us how to set valves and pinion gears. Gave us torque specs and clearance targets. Today they tell us not to drink the battery acid and don't read this book while driving. 

 

We are miles ahead knowing what it 'used to be' if we only apply it, right? People changed. Rules changed, Regulations changed. But the machine still needs what it needs. Motor builds heat when actually working. Heat thins oil. Needs thicker oil in response. In self-defense. Common sense.... 

[newdude]

21 hours ago, Homer1959 said:

Here in canada they recommend 5w30 with no other choice, what about you guys in the usa living in arizona or texas. No opinion needed, i just need to know what is in you owner manual thanks

 

 

5w30 for everyone except for those that see extreme cold so -20F/-29C or colder.  They call for 0w30 for those regions during the cold seasons.   

 

EDIT:  Adding where in the owners manual this comes from, 2025 Sierra HD manual:

 

2025 GMC Sierra /Sierra Denali 2500HD/3500HD Owner Manual

 

Edited September 8, 2025 by newdude

[Z45]

https://gm-techlink.com/?page_id=8647

 

[Homer1959]

2 hours ago, Z45 said:

https://gm-techlink.com/?page_id=8647

 

Z45, you are the man !!! Thanks for this document its really appreciated, thats my kind of reading , ill subscribe to your montly letter

[Pryme]

1 hour ago, Homer1959 said:

Z45, you are the man !!! Thanks for this document its really appreciated, thats my kind of reading , ill subscribe to your montly letter

Did you learn anything different from what others already mentioned in this thread?

[Homer1959]

5 minutes ago, Pryme said:

Did you learn anything different from what others already mentioned in this thread?

  Not about the oil weight and you knew that ..., but take a look at the documents—there's some interesting information there. Don't get me wrong, I'm in no way diminishing the participation and help I've received from the members. This forum is a fantastic place for PU truck owners.

[Chuck FB]

I suppose one consolation is that GM still recommends 5W-30 ( and no doubt for a reason ) for the HD gas trucks and the prior 6.0 gas, where as for a number of years now GM has called for 0w-20 for the half ton V8 engines. Also that GM with the L8T calls for a full synthetic oil which basically a Dexos 1 series 3 oils are. There doesn't seem to be much on the market for a Dexos 1 oil that is thicker other than the 0W-40 from GM. Having said that and that would be Grumpy Bears topic of knowledge, as to oils that meet the Dexos 1 spec and although are listed by the manufacturer as a 5W-30, are on the high side of a 30 grade viscosity at the high end of the operating temp spectrum and a more sheer stable oil. I believe he mentioned High Performance Lubricants brand oil but I don't know if its even available in Canada. 

 

There is another aspect to any of the off the shelf typical oils easy to find ( Dexos 1 spec in this case ) and that is to change the oil more often than what these long drain intervals are suggested by the vehicle manufacturer. Fresh oil that is not sheered down and has all its additives is always going to protect better than oil that has a questionable life span left. 

[No F-bdy Bs]

5/30

 

Don't overthink it. 

[Homer1959]

4 minutes ago, No F-bdy Bs said:

5/30

 

Don't overthink it. 

Oh, I’m done thinking about it, lol. I was just curious since some manufacturers have different specs for the same equipment depending on the region. The dealership will handle those oil changes—it’ll be the first time in my life I’m not climbing under one of my vehicles to do maintenance. I decided to go with GMPP to cover myself for 7 years or 62,000 miles bumper to bumper, so they can’t deny a warranty claim if the engine explodes, lol. Plus, I’ve got 3 free oil changes, enough to cover 3 calls from the oil life monitor. I don’t plan to keep the truck beyond the warranty period, whether by time or mileage.

[Pryme]

9 hours ago, Chuck FB said:

I suppose one consolation is that GM still recommends 5W-30 ( and no doubt for a reason ) for the HD gas trucks and the prior 6.0 gas, where as for a number of years now GM has called for 0w-20 for the half ton V8 engines. Also that GM with the L8T calls for a full synthetic oil which basically a Dexos 1 series 3 oils are. There doesn't seem to be much on the market for a Dexos 1 oil that is thicker other than the 0W-40 from GM. Having said that and that would be Grumpy Bears topic of knowledge, as to oils that meet the Dexos 1 spec and although are listed by the manufacturer as a 5W-30, are on the high side of a 30 grade viscosity at the high end of the operating temp spectrum and a more sheer stable oil. I believe he mentioned High Performance Lubricants brand oil but I don't know if its even available in Canada. 

 

There is another aspect to any of the off the shelf typical oils easy to find ( Dexos 1 spec in this case ) and that is to change the oil more often than what these long drain intervals are suggested by the vehicle manufacturer. Fresh oil that is not sheered down and has all its additives is always going to protect better than oil that has a questionable life span left. 

Changing it at 4-5k miles max is the most important thing. 
all of these extended drain intervals sure seemed to come out just about the time a lot of manufacturers started giving out “free” 2 year maintenance plans with their new vehicles. 
My around town step and fetch is a Corolla and it calls for 10k mile drain intervals. Haha good one. I run 5k and did during the 2yrs of free maintenance too. I’d change one then let them and traded off til it was over at 2 years.  
 

 

[diyer2]

Just do 5k OCI's like Prime said. More frequent oil changes has worked for me for many years. 

[Homer1959]

I appreciate your suggestion guys however like i've said im not planning to keep the truck longer than the warranty period, so GM  will have to live by  the oil life monitor or they will have to pay through their power train or GMPP warranty if the engine blow up.btw i am much more concerned by the tranny and the valve body. My service advisor said that 3 out of 10 truck have a chance to suffer from The stupid valve body, and the parts are still kind of rare